This invention relates to high performance magnetic tape drives for digital data processing systems, and more particularly to a small, rack mounted tape drive.
U.S. Pat. Nos. 3,393,878--Aweida et al and 3,854,674--Herger et al show magnetic tape drives of the type commonly used in digital data processing systems. These tape drives include a supply reel and a take-up reel having parallel axes which are disposed horizontally one with respect to another. The tape drives shown in these patents include tapered isolation pockets, designated 41 in the Aweida et al patent and designated 37 and 38 in the Herger et al patent. These pockets isolate the large amounts of tape from the driving capstan so that the capstan can quickly accelerate and decelerate tape moved past the tape head. The pockets have a wide taper to maintain proper tension on the tape as explained in the first paragraph of column 3 of the Herger et al patent. Because these tape drives are relatively large, there is adequate space in which to provide properly tapered pockets. Recently, smaller rack mounted magnetic tape drives have been used. In these tape drives, the supply and take-up reels are arranged with their axes one above the other and with the threading channel extending vertically between them. The standard size for such rack mounted units is 19" across. Because of limited available space, the geometry of the isolation pocket with respect to the reels is different. Also, only a very limited depth can be provided because of this limited space. The Wangco Mod 14 rack mounted tape drive is one example of a prior art drive of this type.